Climate Bulletin For Sri Lanka (24 September 2021)

 

Highlights          

                   

•  Heavy rainfall is predicted in Central, Sabaragamuwa, Southern and Western provinces during 24th - 28th Sept. Greater likelihood of dry tendency than normal is predicted for southern Sri Lanka from Oct to Dec.

 •  Heavy rainfall was experienced in Eastern, North Central, Sabaragamuwa and Western provinces with max of 135.2 mm in Trincomalee district on 17th Sept

 •  From 14th - 20th Sept, up to 35 km/h Southwesterlieswere experienced across the island.

 • Sea surface temperature was observed above 0.5℃ to the South and 1.00C to the North of Sri Lanka.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 22^nd – 28^th September: 

Total rainfall by Provinces

• 125 mm - Sabaragamuwa, Western
• 115 mm - Southern
• 105 mm - Central
•  95 mm - North Western
•  85 mm - Uva 
•  65 mm - East, North Central
•  55 mm - Northern

From 29^th September – 5^th  October: 

Total rainfall by Provinces:

• 85 mm - Sabaragamuwa, Western
• 75 mm - Central, Southern
• 65 mm - North Western
• 45 mm - Uva
• 35 mm - Eastern, Northern, North Central

MJO based OLR predictions:

For the next 15 days: 

MJO shall be active, thus giving slightly enhanced rainfall from 24^th September – 6^th October. 

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 15, 2021 

Equatorial SSTs were near-to-below average across most of the equatorial Pacific Ocean and were above average in the western Pacific Ocean in mid-September. A large majority of the model forecasts predict a transition from ENSO-neutral to La Niña is favored in the next couple of months and La Niña to continue through the Northern Hemisphere fall and winter.

Indian Sea Sate

Sea surface temperature was observed above 0.5℃ to the South and 1.0⁰C to the North of Sri Lanka. 

Interpretation

Monitoring

Rainfall: 

During the last two weeks, there had been heavy rainfall over the following Provinces: Eastern, North-Central, Sabaragamuwa and Western.

Wind: 

Southwesterly winds prevailed in the sea area and around the island during last week. 

Temperature: 

The temperature anomalies were between 1⁰C – 3⁰C in Central and Sabaragamuwa provinces while near-neutral for the rest of the country last week – driven by the warm SST’s.

Predictions

Rainfall:

During the next week (24^th - 28^th September) heavy rainfall is predicted for Central, Sabaragamuwa, Southern, Western and Central provinces. 

Temperature:

The temperature remains slightly normal for September. During 24^th September – 2^nd October, the temperature remains high especially in the Eastern, Southern and Uva provinces.

Teleconnections:

La Nina -The SST forecast indicates that ENSO-neutral is present and a transition from ENSO-neutral to La Niña is favored in the next couple of months.

MJO shall be active, thus giving slightly enhanced rainfall from 24^th September – 6^th October. 

Seasonal Precipitation: 

October to December is the main rainfall season in Sri Lanka. The consensus predictions has switched from neutral to favoring a dry tendency.  A dry tendency can hurt agricultural production and it adds to farmer difficulties due to the fertilizer bans. However, since this is the wet season the impact will not be as severe. 

However, the bigger impact shall be that it shall reduce the generated hydropower in the coming months. This can hurt the economy due to the scarcity in Foreign Exchange within the country due to the Central Bank regulations.